Fabrication of Continuous Fire Wire Detection Sensor usingNegative Temperature Coefficient Material

Manganese-based spinel semiconducting ceramic was mixed with lanthanum oxide powderand the mixture was characterised for the reproducible negative temperature coefficient (NTC)of resistance behaviour. The same mixture was used for the fabrication of 15 m long continuousthermal detector.  The addition of La2O3 leads to decrease in thermistor constant and activationenergy values, thus giving freedom to fabricate thermal sensors for various temperatureapplications. A 3 m long continuous thermal detector for application in the temperature range275 - 350 oC was fabricated and later coupled to form a continuous unit of 15 m length

Fabrication of Continuous Fire Wire Detection Sensor using Negative Coefficient Material

Manganese-based spinel semiconducting ceramic was mixed with lanthanum oxide powder and the mixture was characterised for the reproducible negative temperature coefficient (NTC) of resistance behaviour. The same mixture was used for the fabrication of 15 m long continuous thermal detector. The addition of La2O3 leads to decrease in thermistor constant and activation energy values, thus giving freedom to fabricate thermal sensors for various temperature applications. A 3 m long continuous thermal detector for application in the temperature range 275 - 350 oC was fabricated and later coupled to form a continuous unit of 15 m length

Effect of surfactant concentration, solvents and particle size on Pi-A isotherm of silica nanoparticles

We present here, the effect of surfactant concentration, different solvents and particle sizes on isotherm of silica nanoparticles at air/water interface. The experiments were performed by Langmuir–Blodgett (LB) technique and pressure ∏–A isotherms were recorded. Silica nanoparticles (NPs) of different sizes namely; 30 nm, 150 nm and 630 nm, were synthesized by Stöber's method and characterized by using scanning electron microscopy to determine their sizes and dispersity. As-synthesized NPs were hydrophobized to varying extents through addition of varying amounts, ranging from 0.5 mg to 1.5 mg, of the cationic surfactant,cetyltrimethylammoniumbromide (CTAB). Effect on lift off area (area/particle) and corresponding yield were investigated and reported. This parametric study can adds on in meeting the requirement of reproducibility of LB films

An optoelectronic instrument for the determination of sulphite in beverages.

The paper describes an optoelectronic device that has been designed and developed to measure the sulphite concentration in beverages for quality evaluation. A selective and sensitive method for determination of sulphite is based on the reaction with pararosaniline acid bleached dye and formaldehyde solution, which gives violet colored complex having absorption maxima at 560 nm. Lambert–Beer’s law is obeyed in the concentration range up to 25 μg/ml (25 ppm) of test solution within an accuracy of ±0.05μg/ml (0.05 ppm). The instrument involves the use of high intensity green light emitting diode (LED) of wavelength 565 nm as light source. BPW21 photodiode having the relative spectral sensitivity above 90% in the range of 500–600 nm has been used as a detector, for the determination of sulphite concentration

One step electrochemical synthesis of goldnanoparticles– polypyrrole composite for application in catechin electrochemical biosensor

An electrochemical biosensor has been fabricated for catechin detection using the nanoparticle–polymer composite as a matrix. The composite has been electrochemically synthesized and tyrosinase enzyme was entrapped during polymerization of the composite material. The composite has been characterized for its morphology, optical, structural, and electrochemical behavior. Studies revealed that the presence of gold nanoparticles (AuNPs) in the polymer matrix resulted in an increase in conductivity, enhanced current intensity and diffusion coefficient. The AuNPs–PPy composite provided large surface area for enzyme immobilization and facilitated electron transfer, evident from almost 10% enhancement in biosensor response in the presence of nanoparticles (NPs). For catechin detection, the biosensor showed well defined redox peaks at 0.24 V/0.14 V for the redox reaction of the hydroxyl group present in the catechol moiety of the catechin and a weak oxidation peak at 0.62 V corresponding to the oxidation of the hydroxyl group present in the central ring of catechin. The linearity was achieved from 1 × 10−9 M to 1 × 10−8 M, with a sensitivity of 6.8 × 10−5 A M−1. The limit of detection (3 × SD/sensitivity) and Km value are 1.2 × 10−9 M and 4.5 × 10−9 M respectively. The response time of the biosensor was about 10–12 s with an optimum pH at 7.0. The biosensor has been tested for catechin detection in water and apple juices and the response was within 10% error

Evaluation of calibration of moisture meter for Indian wheat by microwave oven drying technique and commercial moisture meter

Moisture plays an important role in storage and processing of food grains, cereals and other agricultural products. It is the single most important characteristics of most agricultural products with respect to quality maintenance. This paper describes how to prepare samples for moisture determination, and calibrate a moisture meter for a particular grain. Calibration of a laboratory-developed moisture meter (LDMM) with a a commercial moisture meter (CMM) is also presented in this paper, in order to evaluate its performance. It shows that the values estimated by the LDMM were in good agreement with the moisture content values that are obtained by CMM, and the developed meter has a less than�1% error. It also describes the studies carried out for calibration of the LDMM using a microwave oven drying technique. An evaluation of the calibration performance of LDMM with two different techniques has also been reported. The microwave oven method and dry oven method have been compared for moisture determination of Indian wheat. It has been observed that the microwave method took 10–20 min compared with 18–20 h by the standard dry oven method for moisture determination of Indian wheat. The results obtained by the microwave oven method were compared with those obtained by the dry oven method. No statistical difference was observed between the percentage moisture values of Indian wheat samples by microwave drying and dry oven drying. The accuracy of the developed meter has also been tested by taking different numbers of calibration samples. It was observed that the accuracy increased considerably with an increase in the number of calibration sample

Optoelectronics behaviour of ZnO nanorods for UV detection

In this study ZnO nanorods have been synthesized by a chemical precipitation method. The room temperature UV–Vis absorption spectra of the ZnO nanorods indicated two absorption peaks in the UV region, one in the near UV region and the other attributed to the band gap of ZnO. The Photoluminescence spectra of ZnO nanorods show two emission bands, one ultraviolet emission band at 378 nm and the other in the defect related yellow emission band near 550 nm. The stimulated yellow luminescence of ZnO nanorods were affected by the synthesis time and annealing temperature. The same ZnO nanorods were deposited onto the ITO substrate to form a UV photoconductive detector. The ratio of the UV photogenerated current to dark current was as high as nine times under 3 V bias. Hence, these nanorods can be promising materials in the use of UV radiation detection

Low temperature sensing capability of polyaniline and Mn3O4 composite as NTC material

The paper deals with the synthesis of composite of polyaniline with Mn3O4 via oxidative polymerization of monomer by ammonium persulphate in presence of finely graded (45 μM) Mn3O4. The characterization of composite was done by FT-IR, XRD, TGA, conductivity and TCR. The composite possesses the resistance in the range of kilo-ohms at ambient temperature, which starts decreasing with the increase in temperature and becomes minimum at 170°C and remains constant up to 200°C, thus behaves like semiconductor with respect to temperature resistance characteristics. The factor responsible for decrease in the resistance values during the temperature range of ambient to 170°C is hopping of electrons between Mn2+/Mn3+ and its enhanced mobility due to polyaniline chain. After 200 °C the resistance values of composite again increases slowly, because of waning interaction ofMn3 Ο4 and PANI. Above 300 °C the resistance values increases significantly due to complete decomposition of polyaniline which has been confirmed by thermal analysis. The blend of polyaniline/Mn3O4 was also prepared in the same ratio, the TG of which shows that the blend is just the physical mixture of the two constituents while in case of composite proper interaction is proved, supported by FT-IR, TG and XRD analysis. Thermal analysis shows that the decomposition of polyaniline and its composite is slow in nitrogen atmosphere as compared to air. The thermistor constant B and temperature become linearly dependent. The study shows the potential of composite to act as negative temperature coefficient (NTC) material for thermistor applications and continuous thermocouple

Voltammetric determination of citric acid and quinine hydrochloride using polypyrrole–pentacyanonitrosylferrate/platinum electrode

Cyclic voltammetry was used to investigate the electrochemical behavior of citric acid (CA) and quinine hydrochloride (QH) at a polypyrrole-pentacyanoferrate/Platinum (PPY–PCNFe/Pt) electrode in aqueous medium. The analytical plots obtained were found to be linear in the concentration range between 1.0 and 9.0 mM for both the analyte solutions. The detection limits (3δ) were found to be 1.17 × 10−4 M and 1.08 × 10−5 M for CA and QH analyte solutions, respectively. It was further observed that the diffusion of ionic species into and out of the polymeric film made the PPY–PCNFe/Pt electrode highly electroactive thereby enabling it to efficiently detect the analyte solutions having concentration as low as 1 mM